Like you say, moisture would be a problem. And where there's moisture there can be mould. IMO, I'd try to avoid anything remotely close to a mould problem.
I'd first look at why your vent clogs and try to remedy that. Though there can be some minor buildup on the walls of the vent tube, it shouldn't be clogging. No matter where you run the vent, it's a hazard. Clogs aren't usually predictable.